In applications wherein it is necessary to contain pressurized fluids, resilient metallic seals are used when elastomeric and polymeric materials cannot be used because of extremely high pressures, high temperatures and/or aggressive media. Resilient, metallic seals are produced in different configurations that are designed to meet a variety of operating requirements.
One prior art resilient, metallic seal is known as the axial C-seal. The C-seal, which is available in three basic orientations, was developed as an improvement in flexibility over the hollow metal O-ring. The axial C-seal, which is intended for sealing the space between two concentric cylindrical surfaces, is shown in FIGS. 1A and 1B. As shown in cross-section in FIG. 1A, prior art axial C-seal 10 has an arcuate portion 12, outer sealing surface 16 and inner sealing surface 14. These features are also shown in FIG. 1B which is an enlarged view of a portion of the view of FIG. 1A. Circumferential lines passing through the quadrant points of the section shown in FIG. 1B are known as sealing lines. As with the metal O-ring, the axial C-seal may be used to seal gaps between cylindrical surfaces in mainly static applications.
Other prior art seals have been developed to perform these functions described above. Some of these seals are disclosed in U.S. Pat. Nos. 4,457,523, 4,854,600, 5,799,954, 6,257,594, and 6,446,978. These prior art seals serve their purpose, but they exhibit limitations when required to be pressure-energized and are not capable of accommodating significant lateral misalignments of the cylindrical surfaces to be sealed.
Seals, including prior art axial C-seals, are typically used in couplings and other devices that are part of fluid transmission or containment systems. In the example of a coupling, a rigid hollow proboscis or probe is typically inserted into a hollow receptacle in the fluid transmission system. The receptacle contains a sealing ring or multiple sealing rings which are dilated by insertion of the probe. This dilation creates the required contact stresses for sealing. The contact stresses achieve fluid containment between the two bodies to be sealed together. In some instances, the probe is forced into the receptacle without the centerlines or axes of the two components being properly aligned, as a result of imperfect field installation practices. When this occurs, the probe may displace one side of the axial C-seal to an extent at which the ring may not be sufficiently resilient to elastically deform. As a result, a gap may be formed on the opposite side which results in leakage of fluid when the joint is pressurized.
Some prior art seals, when used to seal the joint of two cylindrical surfaces that are subject to vibrations, have been known to “walk” along the cylindrical surfaces. This is the result of the prior art seals merely lightly engaging both cylindrical surfaces. The “walking” of the seal results in a back-and-forth movement of the seal which causes excessive wear of the seal and the cylindrical surfaces it engages.
Another disadvantage of many prior art seals is poor reliability. This causes problems when repeated disengagements and insertions of probes are necessary.
A further disadvantage is that some pressure-energized prior art seals are extensively plastically deformed at installation and have little elastic recovery (i.e. springback) from their maximum compressed state, usually less than 3% of their free or uncompressed height.
What is needed is a new and improved seal that overcomes the aforesaid deficiencies and problems of the prior art seals.